fix: harden Turtle movement block parser with bounds checks

The Turtle parseMovementBlock had no bounds checking on any reads.
Since Packet::readUInt8() returns 0 past the end without failing, the
parser could "succeed" with all-zero garbage data, then subsequent
parseUpdateFields would read from wrong positions, producing
"truncated field value" and "truncated update mask" errors.

Added bounds checks before every conditional read section (transport,
swimming pitch, fall time, jumping, spline elevation, speeds, spline
data, tail flags). Also removed the WotLK movement block fallback from
the Turtle parser chain — WotLK format is fundamentally incompatible
(uint16 flags, 9 speeds) and false-positive parses corrupt NPC data.
Also changed spline pointCount > 256 from cap-to-zero to return false
so the parser correctly fails instead of silently dropping waypoints.

src/game/packet_parsers_classic.cpp

@@ -1918,6 +1918,9 @@ namespace TurtleMoveFlags {
 }
 
 bool TurtlePacketParsers::parseMovementBlock(network::Packet& packet, UpdateBlock& block) {
+    auto rem = [&]() -> size_t { return packet.getSize() - packet.getReadPos(); };
+    if (rem() < 1) return false;
+
     uint8_t updateFlags = packet.readUInt8();
     block.updateFlags = static_cast<uint16_t>(updateFlags);
 
@@ -1931,6 +1934,8 @@ bool TurtlePacketParsers::parseMovementBlock(network::Packet& packet, UpdateBloc
     const uint8_t UPDATEFLAG_HAS_POSITION    = 0x40;
 
     if (updateFlags & UPDATEFLAG_LIVING) {
+        // Minimum: moveFlags(4)+time(4)+position(16)+fallTime(4)+speeds(24) = 52 bytes
+        if (rem() < 52) return false;
         size_t livingStart = packet.getReadPos();
 
         uint32_t moveFlags = packet.readUInt32();
@@ -1949,8 +1954,10 @@ bool TurtlePacketParsers::parseMovementBlock(network::Packet& packet, UpdateBloc
 
         // Transport — Classic flag position 0x02000000
         if (moveFlags & TurtleMoveFlags::ONTRANSPORT) {
+            if (rem() < 1) return false; // PackedGuid mask byte
             block.onTransport = true;
             block.transportGuid = UpdateObjectParser::readPackedGuid(packet);
+            if (rem() < 20) return false; // 4 floats + u32 timestamp
             block.transportX = packet.readFloat();
             block.transportY = packet.readFloat();
             block.transportZ = packet.readFloat();
@@ -1960,14 +1967,17 @@ bool TurtlePacketParsers::parseMovementBlock(network::Packet& packet, UpdateBloc
 
         // Pitch (swimming only, Classic-style)
         if (moveFlags & TurtleMoveFlags::SWIMMING) {
+            if (rem() < 4) return false;
             /*float pitch =*/ packet.readFloat();
         }
 
         // Fall time (always present)
+        if (rem() < 4) return false;
         /*uint32_t fallTime =*/ packet.readUInt32();
 
         // Jump data
         if (moveFlags & TurtleMoveFlags::JUMPING) {
+            if (rem() < 16) return false;
             /*float jumpVelocity =*/ packet.readFloat();
             /*float jumpSinAngle =*/ packet.readFloat();
             /*float jumpCosAngle =*/ packet.readFloat();
@@ -1976,10 +1986,12 @@ bool TurtlePacketParsers::parseMovementBlock(network::Packet& packet, UpdateBloc
 
         // Spline elevation
         if (moveFlags & TurtleMoveFlags::SPLINE_ELEVATION) {
+            if (rem() < 4) return false;
             /*float splineElevation =*/ packet.readFloat();
         }
 
         // Turtle: 6 speeds (same as Classic — no flight speeds)
+        if (rem() < 24) return false; // 6 × float
         float walkSpeed = packet.readFloat();
         float runSpeed = packet.readFloat();
         float runBackSpeed = packet.readFloat();
@@ -1997,17 +2009,23 @@ bool TurtlePacketParsers::parseMovementBlock(network::Packet& packet, UpdateBloc
         bool hasSpline = (moveFlags & TurtleMoveFlags::SPLINE_CLASSIC) ||
                          (moveFlags & TurtleMoveFlags::SPLINE_TBC);
         if (hasSpline) {
+            if (rem() < 4) return false;
             uint32_t splineFlags = packet.readUInt32();
             LOG_DEBUG("  [Turtle] Spline: flags=0x", std::hex, splineFlags, std::dec);
 
             if (splineFlags & 0x00010000) {
+                if (rem() < 12) return false;
                 packet.readFloat(); packet.readFloat(); packet.readFloat();
             } else if (splineFlags & 0x00020000) {
+                if (rem() < 8) return false;
                 packet.readUInt64();
             } else if (splineFlags & 0x00040000) {
+                if (rem() < 4) return false;
                 packet.readFloat();
             }
 
+            // timePassed + duration + splineId + pointCount = 16 bytes
+            if (rem() < 16) return false;
             /*uint32_t timePassed =*/ packet.readUInt32();
             /*uint32_t duration =*/ packet.readUInt32();
             /*uint32_t splineId =*/ packet.readUInt32();
@@ -2018,10 +2036,12 @@ bool TurtlePacketParsers::parseMovementBlock(network::Packet& packet, UpdateBloc
                 ++badTurtleSplineCount;
                 if (badTurtleSplineCount <= 5 || (badTurtleSplineCount % 100) == 0) {
                     LOG_WARNING("  [Turtle] Spline pointCount=", pointCount,
-                                " exceeds max, capping (occurrence=", badTurtleSplineCount, ")");
+                                " exceeds max (occurrence=", badTurtleSplineCount, ")");
                 }
-                pointCount = 0;
+                return false;
             }
+            // points + endPoint
+            if (rem() < static_cast<size_t>(pointCount) * 12 + 12) return false;
             for (uint32_t i = 0; i < pointCount; i++) {
                 packet.readFloat(); packet.readFloat(); packet.readFloat();
             }
@@ -2034,6 +2054,7 @@ bool TurtlePacketParsers::parseMovementBlock(network::Packet& packet, UpdateBloc
                   " bytes, readPos now=", packet.getReadPos());
     }
     else if (updateFlags & UPDATEFLAG_HAS_POSITION) {
+        if (rem() < 16) return false;
         block.x = packet.readFloat();
         block.y = packet.readFloat();
         block.z = packet.readFloat();
@@ -2045,18 +2066,22 @@ bool TurtlePacketParsers::parseMovementBlock(network::Packet& packet, UpdateBloc
 
     // High GUID — 1×u32
     if (updateFlags & UPDATEFLAG_HIGHGUID) {
+        if (rem() < 4) return false;
         /*uint32_t highGuid =*/ packet.readUInt32();
     }
 
     if (updateFlags & UPDATEFLAG_ALL) {
+        if (rem() < 4) return false;
         /*uint32_t unkAll =*/ packet.readUInt32();
     }
 
     if (updateFlags & UPDATEFLAG_MELEE_ATTACKING) {
+        if (rem() < 1) return false;
         /*uint64_t meleeTargetGuid =*/ UpdateObjectParser::readPackedGuid(packet);
     }
 
     if (updateFlags & UPDATEFLAG_TRANSPORT) {
+        if (rem() < 4) return false;
         /*uint32_t transportTime =*/ packet.readUInt32();
     }
 
@@ -2185,12 +2210,10 @@ bool TurtlePacketParsers::parseUpdateObject(network::Packet& packet, UpdateObjec
                                 return this->TbcPacketParsers::parseMovementBlock(p, b);
                             }, "tbc");
                     }
-                    if (!ok) {
+                    // NOTE: Do NOT fall back to WotLK parseMovementBlock here.
-                        ok = parseMovementVariant(
+                    // WotLK uses uint16 updateFlags and 9 speeds vs Classic's uint8
-                            [](network::Packet& p, UpdateBlock& b) {
+                    // and 6 speeds. A false-positive WotLK parse consumes wrong bytes,
-                                return UpdateObjectParser::parseMovementBlock(p, b);
+                    // corrupting subsequent update fields and losing NPC data.
-                            }, "wotlk");
-                    }
                     break;
                 case UpdateType::OUT_OF_RANGE_OBJECTS:
                 case UpdateType::NEAR_OBJECTS:

src/game/world_packets.cpp

@@ -1024,7 +1024,7 @@ bool UpdateObjectParser::parseMovementBlock(network::Packet& packet, UpdateBlock
             /*float splineElevation =*/ packet.readFloat();
         }
 
-        // Speeds (7 speed values)
+        // Speeds (9 values in WotLK: walk/run/runBack/swim/swimBack/flight/flightBack/turn/pitch)
         /*float walkSpeed =*/ packet.readFloat();
         float runSpeed = packet.readFloat();
         /*float runBackSpeed =*/ packet.readFloat();